The quality of foam is dependent on a plurality of environmental and installation parameters. This applies in particular to the production of polyurethane foam.
Various computer-aided processes for quality assurance in the production of polyurethane foam have become known, such as for example from “Software to Manage a Continuous Production of Flexible Polyurethane Foams by Slabstock Technology”, Salvatore Consoli, Journal of Cellular Plastics, volume 33, March 1997, page 102, “Foam Roadmap On-Line Answemostics”, James D. Shoup, Polyurethane 1995, Sep. 26-29, 1995, pages 489, 490 and “Mathematical Property Prediction Models for Flexible Polyurethane Foams”, Reinhart Schiffauer, Adv. Urethane Sci. Techn., 14 (1998), pages 1 to 44.
Expert systems for processing process parameters in RIM processing have also been disclosed by “Experten mit System, Prozesssteuerung des PUR-RRIM-Verfahrens zur Herstellung von Karosserieauβenteilen” [Experts with system; process control of the PU-RRIM process for the production of exterior bodywork parts], F. Schnabel, Sulzbach, K.-H. Dörner, Kunststoffe, volume 88, October 1998 and “PUR-Teile kostengünstig fertigen, Stand der Polyurethan-RRIM-Technologie” [Low-cost production of PU parts, status of polyurethane RRIM technology], Karl-Heinz Dörner, Hans Joachim Meiners, Hans-Joachim Ludwig, Kunststoffe, volume 91, April/2001. These expert systems are apparently able to make predictions with regard to product properties, process monitoring, quality assurance and preventive maintenance.
DE 28 19 709 B1 furthermore describes a process for the continuous production of foam sheets provided with facing layers, in which foam thickness is measured with ultrasound transversely to the conveying direction. The production installation is then controlled via conveyor belt speed and/or the applied quantity of foam.
DE 102 37 005 A1 describes a process for a continuous slabstock foam process, in which the actual rise heights are continuously measured along the conveying apparatus. A control variable for controlling the slabstock foam process is determined as a function of possible deviations between the actual rise heights and predetermined nominal rise heights.
Temperature measurement methods, in particular contactless temperature measurement, have long been known in the art. Pyrometers are used to evaluate the infrared radiation emitted from the measured object. In this manner, the surface temperature of for example continuous belt installations, plastics extruders, conveyor belts or calenders may be monitored contactlessly.
Different types of installation for the production of slabstock foam and other foams are also known in the art. Examples are the Planiblock, UBT, QFM, Draka-Petzetakis, Maxfoam, Vertifoam Edge Control and VPF processes. In these types of installations, flexible polyurethane foam is produced in a continuous rectangular process. Rigid foam composite sheets with flexible or rigid facing layers are produced on continuously operated double conveyor installations.
DE 691 19 244 T2, DE 692 17 671 T2 and U.S. Pat. No. 4,492,664 A furthermore disclose various apparatuses for the continuous production of polyurethane foam blocks. DE 696 10 885 T2 discloses another apparatus for the production of polyurethane foam. DE 38 19 940 A1, DE 196 49 829 A1, DE 43 15 874 A1 and DE 195 06 671 C2 disclose various processes for the production of polyurethane foams on such installations.